A lithium-battery powered utility vehicle includes a traction control system having a traction controller, a primary contactor and an electric motor. When a driver pushes down on a foot pedal, the traction controller sends a primary contactor signal to the primary contactor that closes the primary contactor thus connecting a lithium-battery pack to the electric motor to provide electric power to the electric motor.
The lithium-battery pack includes a lithium-battery controller, a secondary contactor and a lithium battery. The secondary contactor of the lithium-battery pack is different from the primary contactor of the traction control system although both are high-current electro-magnetic contactors capable of carrying high current for the electric motor. When the remaining amount of charge in the lithium battery drops to a low level, the lithium-battery controller turns off a secondary contactor signal that holds the secondary contactor closed. As a result, the secondary contactor opens thus preventing further discharging of the lithium battery.